Bradley Smoker PLC-5 user manual Transferring Block-Transfer Data to Controller-Resident I/O

5-4Communicating with Controller-Resident I/O

If your application cannot support this configuration, condition the immediate I/O instructions with the control bits of the adjacent block-transfer module. This technique helps make certain that an adjacent block-transfer module is not performing a block-transfer while an immediate I/O instruction is executing in its adjacent input module.

Transferring Block-Transfer Data to Controller-Resident I/O

The controller performs block-transfers at the same time as it scans the program.

Block-transfers to controller-resident local I/O follow these procedures:

•Block-transfer requests are queued for the addressed controller-resident local I/O rack.

•The active buffer continuously handles all block-transfer modules whose block-transfer instructions were enabled in the program scan via the queue scan in the order the requests were queued.

•Block-transfers of I/O data can finish and the done bit can be set anytime during the program scan.

The controller runs all enabled block-transfers of I/O data to controller-resident I/O continuously as each block-transfer request enters the active buffer.

Housekeeping

Controller-

Resident

Rack 0

Multiple	1
Block Transfers
	Q

BTR or BTW Data

A 2

Q = queue

A = active buffer (block-transfer data buffered here)

Interrupt from STI or Fault Routine

Program

Scan

Configuring the System for Controller-Resident I/O

To configure the system for controller-resident local I/O, you need to set the I/O chassis switch to indicate the rack-addressing mode. The addressing mode determines the number of controller-resident rack numbers used based on the number of slots in the chassis. For more information on addressing modes, see chapter 4. To set the I/O chassis switch, see Appendix E.

The controller-resident rack address defaults to rack 0. If needed, you can set it for rack 1 by setting user control bit 2 (S26:2) on the controller configuration screen in your programming software. If you select rack 1 as the controller-resident rack, rack 0 becomes unavailable for your system.

Publication 1785-UM012D-EN-P - July 2005